Repellent electrode for electron repelling

ABSTRACT

The current disclosure is directed to a repellent electrode used in a source arc chamber of an ion implanter. The repellent electrode includes a shaft and a repellent body having a repellent surface. The repellent surface has a surface shape that substantially fits the shape of the inner chamber space of the source arc chamber where the repellent body is positioned. A gap between the edge of the repellent body and the inner sidewall of the source arc chamber is minimized to a threshold level that is maintained to avoid a short between the conductive repellent body and the conductive inner sidewall of the source arc chamber.

BACKGROUND

Ion implantation is a semiconductor wafer fabrication process by whichions of an element are accelerated and implanted into target regions ona wafer, thereby adjusting the electrical properties of the targetregions on the wafer. Besides semiconductor device fabrication, ionimplantation is also used in metal surface finishing and materialpreparations to improve the mechanical, chemical and/or electricalproperties of the targets receiving the implanted ions. For example, theions implanted into a target can alter the elemental composition of thetarget, and can also cause changes in chemical and physical property viathe energy impinged into the target together with the ions.

Ion implantation may be achieved through ion implanters. An ionimplanter usually include a source arc chamber in which an electricaldischarge interacts with a gas to create a plasma of a variety of ionspecies, including a desired ion specie to be impinged into a target,e.g., a target region on a semiconductor wafer. The ion species areextracted from the source arc chamber and are then filtered to obtainthe desired ion species. The desired ion species are further acceleratedand directed to the target for implanting.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates, in a schematic view, an ion implanter;

FIG. 2A is an exploded side view of an example ion source module;

FIG. 2B is a transversal sectional view of the example ion source moduleof FIG. 2A;

FIG. 3 is an example repellent electrode;

FIG. 4 is an exploded image of the example repellent electrode of FIG. 3installed in a source arc chamber in comparison with a conventionalrepellent electrode;

FIG. 5 is an example controller.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the present disclosure. Specific embodiments or examples ofcomponents and arrangements are described below to simplify the presentdisclosure. These are, of course, merely examples and are not intendedto be limiting. For example, dimensions of elements are not limited tothe disclosed range or values, but may depend upon process conditionsand/or desired properties of the device. Moreover, the formation of afirst feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed interposing the first and secondfeatures, such that the first and second features may not be in directcontact. Various features may be arbitrarily drawn in different scalesfor simplicity and clarity. In the accompanied drawings, somelayers/features may be omitted for simplification.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.” Further, inthe following fabrication process, there may be one or more additionaloperations in/between the described operations, and the order ofoperations may be changed. In the present disclosure, a phrase “one ofA, B and C” means “A, B and/or C” (A, B, C, A and B, A and C, B and C,or A, B and C), and does not mean one element from A, one element from Band one element from C, unless otherwise described.

The current disclosure is directed to a repellent electrode used in asource arc chamber of an ion implanter. The repellent electrode includesa shaft and a repellent body having a repellent surface. The repellentsurface has a surface shape that substantially mirrors the shape of theinner chamber space of the source arc chamber where the repellent bodyis positioned. A gap between the edge of the repellent body and theinner sidewall of the source arc chamber is minimized to a thresholdlevel that is maintained to avoid short between the conductive repellentbody and the conductive inner sidewall of the source arc chamber. Insome embodiments, the gap has a substantially uniform dimension indifferent directions. That is, the shape of the repellent surfacesubstantially matches or mirrors the shape of a transversal plane of theinner chamber space where the repellent surface is positioned, while therepellent surface has a slightly smaller dimension than the transversalplane of the inner chamber space. For example, in a case the transversalplane of the inner chamber space is round, the repellent surface is around having a smaller diameter, e.g., a diameter about 1 mm to about 3mm smaller than that of the inner chamber space. In a case thetransversal plane of the inner chamber space is square, the repellentsurface is substantially a smaller square, e.g., having a side about 1mm to about 3 mm smaller than a side of the transversal plane. In a casethe transversal plane of the inner chamber space is rectangular, therepellent surface is substantially a smaller rectangular, e.g., havingeach side about 1 mm to about 3 mm smaller than the corresponding sideof the transversal plane. If the transversal plane of the inner chamberspace is oval, the repellent surface is a smaller oval. When the shapeof the repellent surface mirrors or matches the shape of transversalplane of the inner chamber space of the source arc chamber, theeffective surface for repelling thermal electrons is increased, whichthus increases the odds that an electron is repelled back by therepellant electrode. Increasing the number of electrons repelled by therepellent electrode results the gas in the arc chamber being ionizedmore efficiently.

FIG. 1 depicts, in a schematic manner, an ion implanter system 100. Thesystem 100 is housed in a high-vacuum environment 102. The ion implantersystem 100 may comprise an ion source module 110, an extraction module120, an ion filtering module 130, an ion acceleration/decelerationmodule 140, an ion analyzer module 150 including analyzer magnets 152and a beamguide 154, and a corrector module 160. In operation, a dopantgas (also referred to as “precursor gas”) that contains the desiredelements to be implanted into a target 170, e.g., a semiconductor wafer,is electrically excited in the ion source module 110 to generate ions.Ions 10 generated by the ion source module 110 are extracted out of theion source module 110 by the extraction module 120 and then pass throughthe ion filtering module 130 to filter out contaminant particles. Theions 10 are then accelerated or decelerated, by the ionacceleration/deceleration module 140 into the ion analyzer module 150.The ion analyzer module 150 sorts out or rejects ions of aninappropriate charge-to-mass ratio. For example, the ion analyzer module150 includes analyzer magnets 152 and a beamguide 154. The beam guide154 (or a resolving slit) includes curved sidewalls into which ions ofan undesired mass-to-charge ratio collide as they are propagated throughthe beam guide 154 by one or more magnetic fields generated by themagnet(s) of the analyzer magnets 152. As such, only the desired ionspecies 10 pass through the beam guide 154 and then the corrector module160. The corrector module 160 shapes the profile of the beam 10 of thedesired ion species before they hit the target 170 held on an endstation 180.

The ion implanter system 100 also includes a controller 190 thatcontrols the operation of one or more components of the ion implantersystem 100.

FIG. 2A shows an exploded side cross-sectional view, e.g., in the x-zplane, of an example ion source module 110. As shown in FIG. 2A, the ionsource module 110 includes a source arc chamber 210 defining an innerchamber space 212. Specifically, the inner chamber space 212 issurrounded by two opposing end walls 214, 216 and one or more sidewall218 of the source arc chamber 210. A cathode electrode 220 and arepellent electrode 230 are positioned within the inner chamber space212, in some embodiment, each adjacent to an end wall 214, 216,respectively, as shown in FIG. 2A. It should be appreciated that otherarrangements of the cathode electrode 220 and/or the repellent electrode230 are also possible and included in the disclosure. For example, thecathode electrode 220 may be positioned on the sidewall 218 of thesource arc chamber 210. An aperture 240 and a gas inlet 250 arepositioned on the sidewall 218 of the source arc chamber.

Dopant gas Gas is introduced into the inner chamber space 212 throughthe gas inlet 250 and stays substantially uniformly within the innerchamber space 212.

The cathode electrode 220 normally includes or is coupled with, eitheras an integrated part or as a separate element, a filament element. FIG.2A shows the cathode electrode 220 as a filament element forillustrative purposes, which does not limit the shapes or configurationsof the cathode electrode 220. The filament element is connected to apower supply (not shown) to heat the cathode electrode via electronbombardment to achieve thermionic emission of electrons e⁻. Thegenerated electrons e⁻ are attracted away from the cathode electrodethrough one or more of the electric fields of the end walls 214, 216 andthe sidewall 218 or the repelling potential of the cathode electrode220. In some embodiments, a magnetic field is also created within theinner chamber space 212 which drives the electrons to travel toward therepellent electrode 230.

The repellent electrode 230 includes a repellent surface 232 that facesaway from the end wall 216 that is adjacent to the repellent electrode230 and faces toward the electrons e⁻ travelling from the cathodeelectrode 220. The repellent surface 232 includes an electricalconductive material that is connected to a power supply to generate anelectric potential designed to repel the electrons e⁻. For example,because the electrons e⁻ include negative charges, the repellent surface232 is configured to generate a negative potential to repel theelectrons e⁻. In some embodiments, the cathode electrode 220 may alsoinclude a negative potential to repel the electrons e⁻ away from thecathode electrode 220. As such, the travelling of the electrons e⁻ backand forth between the cathode electrode 220 and the repellent electrode230 increases the odds that the electrons collide into and interact withthe dopant gas Gas in the inner chamber space 212. Such interactionsgenerate a plasma of multiple ion species including the ion speciesdesired to be implanted into the target 180, e.g., a semiconductorwafer.

The generated ion species are extracted from the source arc chamber 210through the aperture 240.

The electrons e⁻ that are “missed” by the repellent surface 232 will notbe repelled back to interact with the dopant gas Gas and will beabsorbed by one or more of the end wall 216 or the sidewall 218. Toincrease the odds that electrons e⁻ are repelled back by the repellentsurface 232, the current disclosure provides a repellent surface 232that substantially fits a transversal plane of the inner chamber space212 where the repellent surface 232 is positioned at.

FIG. 2B shows a transversal sectional view of the source arc chamber210, from cutting line B-B in FIG. 2A, and the repellent surface 232. Asshown in FIG. 2B, a shape of the repellent surface 232 substantiallymirrors or matches a shape of the inner chamber space 212 in thetransversal cross-sectional plane B-B. In the description herein, theshape of the inner chamber space 212 in the transversal cross-sectionalplane B-B is referred to as “the transversal plane 260” for descriptionpurposes. In FIG. 2B, it is shown, as an illustrative example, that thetransversal plane 260 is orthogonal to the sidewall 218 of the innerchamber space 212. This illustrative example does not limit the scope ofthe disclosure. In some embodiments, the transversal plane 260 isdefined as a plane within the inner chamber space 212 along which therepellent electrode 230 is positioned. In a case that the repellentelectrode 230 is positioned with an angle (other than 90 degree) to thesidewall 218, the transversal plane 260 also has a same angle withrespect to the sidewall 218. In some embodiments, the shape of therepellent surface 232 substantially matches or mirrors the shape of thetransversal plane 260, while the repellent surface 232 has a smallerdimension than the transversal plane 260. For example, as shown in FIG.2B, the repellent surface 232 is smaller than the transversal plane 260by about 2 mm to about 4 mm in the x-axis direction, e.g., a gap space262 of about 1 mm to about 2 mmmm separating an edge of the repellentsurface 232 from the sidewall 218 of the source arc chamber 210 at eachside of the repellent surface 232 in the x-axis direction. The repellentsurface 232 is smaller than the transversal plane 260 by about 2 mm toabout 4 mm in the y-axis direction, e.g., the gap space 262 of about 1mm to about 2 mm separating an edge of the repellent surface 232 fromthe sidewall 218 of the source arc chamber 210 at each side of therepellent surface 232 in the y-axis direction. In some embodiments, thegap space 262 between the sidewall 218 and an edge 234 of the repellentelectrode 230 is minimized to a lower threshold size such that thesurface area of the repellent surface 232 is maximized. The lowerthreshold size of the gap space 262, here about 1 mm to about 2 mm, ismaintained to avoid undesirable contact or short between an edge of therepellent electrode 230 and the source arc chamber 210, or specificallythe sidewall 218 of the source arc chamber 210. The range of about 1 mmto about 2 mm is critical to ensure that the repellent electrode 230 ispositioned within the inner chamber space 212 without physicallycontacting the sidewall 218. FIG. 2B shows that the transversal plane260 of the inner chamber space 212 and the repellent surface 232 areboth substantially rectangular, which is an illustrative example anddoes not limit the scope of the disclosure.

The transversal plane 260 of the inner chamber space 212, or theinternal sidewall 218, may include different shapes or profiles. Therepellent surface 232 may also include different shapes that match ormirror the shapes or profiles of the transversal plane 260. An surfacearea of the repellent surface 232 is smaller than a surface area of thetransversal plane 260. For example, in a case the transversal plane 260of the inner chamber space 212 is round in shape, the repellent surface232 is also round with a smaller dimension, e.g., having a diameterabout 2 mm to about 4 mm smaller than a diameter of the roundtransversal plane 260. In a case the transversal plane 260 of the innerchamber space 212 is substantially a square, the repellent surface 260is also a square that is smaller in dimension, e.g., having each sideabout 2 mm to about 4 mm smaller than the corresponding side of thetransversal plane 260. The transversal plane 260 and the repellentsurface 232 may also be other polygonal shapes, oval shapes, orirregular shapes.

In accordance with disclosed embodiments, the repellent surface 232 fitswithin the transversal plane 260 with a minimized gap space 262separating the repellent surface 232 from the sidewall 218. In someembodiments, the size of the gap space 262, measured as a distancebetween a point at the edge 234 of the repellent electrode 230 and anearest point at the sidewall 218, is substantially consistent oruniform at various directions and for various points at the edge 234. Abasis for this substantially uniform gap size of the gap space 262 isthat the gap space 262 is similarly minimized at various directions. Insome embodiments, a size of the gap 262 is smaller than 2 mm to ensurethat the size of the repellent surface 232 is sufficiently large toenhance repelling of the electrons e⁻. In some embodiments, a size ofthe gap 262, i.e., a distance between the repellent electrode 230 andthe sidewall 218, is in a range between about 1 mm to about 2 mm suchthat the size of the repellent surface 232 is sufficiently large toenhance repelling of the electrons e⁻ and the gap 262 is sufficientlylarge to avoid an edge of the repellent electrode 230 contacting thesidewall 218.

In some embodiments, a polygonal repellent surface 232 includes arounded corner portion 270. The rounded corner portion 270 is designedto improve the electrical properties of the polygonal repellent surface232. For example, the rounded corner portion 270 is less likely to causepoint discharge. In some embodiment, the internal corner 272 of thesidewall 218 is also rounded. That is, the transversal plane 260 alsoincludes rounded corners. The rounded corner portion 270 substantiallyfits the rounded internal corner 272 of the sidewall 218 to minimize thegap space 262 at the rounded internal corner 272.

FIG. 3 is an example repellent electrode 230. FIG. 3 includes a topview, a side view and a prospective view of the repellent electrode 230.The example repellent electrode 230 includes a repellent body 310 and ashaft 320. The repellent body 310 includes a repellent surface 232, arepellent edge 234 and a back surface 312. In some embodiments, theshaft 320 is positioned at a center 314 of the back surface 312 of therepellent body 310. The repellent body 310 is made of an electricalconductive material, e.g., tungsten or other suitable conductivematerials like titanium alloy. The shaft 320 includes a first portion322 that is configured to be positioned within the inner chamber space212 and a second portion 324 that is configured to extend through theend wall 216 (FIG. 2) of the source arc chamber 210 and be coupled withan anchoring element (not shown) that secures the repellent electrode230 onto the source arc chamber 210. The anchoring element is aninsulator, e.g., a ceramic material. One or more of the first portion322 or the second portion 324 is made of an insulator material, e.g., aceramic material like aluminum oxide. In an example embodiment, thefirst portion 322 is about 2 mm in length and the second portion isabout 10 mm in length. The first portion 322 may have a diameter ofabout 3.175 mm. The second portion 324 may include a same diameter sizeas the first portion 322 or may include a diameter that is smaller,shown in dotted lines, than that of the first portion 322. For example,the second portion 324 may include a diameter of about 3.0 mm. Thesmaller diameter of the second portion enables a smaller opening on theend wall 216 for the second portion 324 to pass through and for thelarger first portion 322 to cover the opening.

The corners 270 on the repellent surface 232 are rounded (the corners326 on the back surface 312 are similarly rounded). In some embodiments,the rounded corner 270 represents no more than ¼ of a perimeter of acircle. In some embodiments, the rounded corner 314 represents about ⅛of a perimeter of a circle. The represented circle may have a diameterof about 4 mm or larger such that the rounded corner 270 is sufficientlysmooth to avoid point discharge.

In some embodiments, a corner 332 between the back surface 312 and theedge 234 is also rounded, as shown in dotted line. A corner 334 betweenthe repellent surface 232 and the edge 234 is also rounded, as shown indotted line. In some embodiments, the rounded corner 332 represents nomore than ¼ of a perimeter of a round. In some embodiments, the roundedcorner 332 represents about ⅛ of a perimeter of a circle. Therepresented circle may have a diameter of about 4 mm or larger such thatthe rounded corner 334 is sufficiently smooth to avoid point discharge.In some embodiments, the rounded corner 334 represents about ⅛ of aperimeter of a circle. The represented circle may have a diameter ofabout 4 mm or larger such that the rounded corner 332 is sufficientlysmooth to avoid point discharge. In some embodiments, athree-dimensional profile of a corner portion of the repellent electrode230 combines or includes rounded corners 270, 332 and 334 and issubstantially dome shaped. The dome-shaped corner portion helps toprevent electrical discharge.

In some embodiments, the repellent surface 232 is substantiallyrectangular with rounded corners 270. The repellent surface 232 includesa size of about 19 to about 21.5 mm in one dimension and about 25.5 toabout 28 mm in another dimension. A surface area of the repellentsurface 232 is about 484.5 mm² to about 602 mm². A thickness of therepellent body 310 in the z-axis is about 3 mm to about 3.75 mm.

In some embodiments, the shape of the repellent surface 232 follows thatof the transversal plane 260 with a gap 262 being maintained as minimum,e.g., in a range between about 1 mm and about 2 mm or other minimizedsizes based on other system configurations. For example, in a case thatthe transversal plane 260 is oval, the repellent surface 232 is alsooval of substantially a same shape but with a smaller dimension. In acase that the transversal plane 260 is a polygonal shape having 3 sidesor 5 or more sides, the repellent surface 232 is substantially the samepolygonal shape with rounded corners and a smaller dimension. The gap262 is maintained as minimum no matter the shape of the transversalplane 260 or the shape of the repellent surface 232.

FIG. 4 shows an exploded image of an example repellent electrode 400 ofthe disclosed technique as compared to an example round repellentelectrode 500 installed in a same source arc chamber. As shown in FIG.4, the round repellent electrode 500 does not mirror the source arcchamber as compared to the example repellent electrode 400. Because theshape of the repellent surface 410 of the repellent electrode 400mirrors or matches the shape of the transversal plane 422 of the innerchamber space 420 of a source arc chamber, a gap 424 between therepellent surface 410 of the repellent electrode 400 and the sidewall ofthe source arc chamber is minimized. The surface area of the repellentelectrode 400 is much larger than the surface area of the roundrepellent electrode 500. Because the shape of the repellent surface ofthe repellent electrode 500 does not fit or mirror the shape of thetransversal plane where the repellent electrode 500 is positioned in,here round versus rectangular, the repellent electrode 500 is not ableto minimize the gap between the conventional repellent electrode 500 andthe sidewall of the source arc chamber. The example repellent electrode400 increased the repellent surface area and the odds that electrons arerepelled back toward the dopant gas in the source arc chamber togenerate ions.

In the description herein, an example polygonal repellent surface 232 isdescribed as having a rounded corner. Specifically, the rounded corneris convex. Other example embodiments are also possible and are includedin the scope of the disclosure. For example, the meeting points betweenthe sides of the substantially polygon-shaped repellent surface 232 mayalso be concaves. That is, the rounded corner may include concaveportions toward a center of the repellent surface 232. The roundedshapes of the concave portions prevent electrical discharges fromoccurring. Other shapes of the meeting points between sides of thesubstantially polygon-shaped repellent surface 232 are also possible,which are configured to prevent electrical discharge from occurring atthe meeting points.

FIG. 5 shows a block diagram of an example controller 190 forcontrolling the ion implanter system 100 in accordance with someembodiments. Controller 190 includes a hardware processor 702 and anon-transitory, computer readable storage medium 704 encoded with, i.e.,storing, computer program code 706, i.e., a set of executableinstructions. Computer readable storage medium 704 is also encoded withinstructions 707 for interfacing with components of ion implanter system100. The processor 702 is electrically coupled to the computer readablestorage medium 704 via a bus 708. The processor 702 is also electricallycoupled to an I/O interface 710 by bus 708. A network interface 712 isalso electrically connected to the processor 702 via bus 708. Networkinterface 712 is connected to a network 714, so that processor 702 andcomputer readable storage medium 704 are capable of connecting toexternal elements via network 714. The processor 702 is configured toexecute the computer program code 706 encoded in the computer readablestorage medium 704 in order to cause controller 190 to be usable forperforming a portion or all of the operations as described with respectto Ion implanter system 100.

In some embodiments, the processor 702 is a central processing unit(CPU), a multi-processor, a distributed processing system, anapplication specific integrated circuit (ASIC), and/or a suitableprocessing unit.

In some embodiments, the computer readable storage medium 704 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example, the computerreadable storage medium 704 includes a semiconductor or solid-statememory, a magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or anoptical disk. In some embodiments using optical disks, the computerreadable storage medium 704 includes a compact disk-read only memory(CD-ROM), a compact disk-read/write (CD-R/W), and/or a digital videodisc (DVD).

In some embodiments, the storage medium 704 stores the computer programcode 706 configured to cause controller 190 to perform the operations asdescribed with respect to ion implanter system 100. In some embodiments,the storage medium 704 also stores information needed for performing theoperations as described with respect to Ion implanter system 100, suchas a sensor parameter 716, a target temperature parameter 718, athreshold temperature parameter 720 and/or a set of executableinstructions to perform the operation as described with respect to Ionimplanter system 100.

In some embodiments, the storage medium 704 stores instructions 707 forinterfacing with Ion implanter system 100. The instructions 707 enableprocessor 702 to generate operating instructions readable by elements ofthe Ion implanter system 100 to effectively implement the operations asdescribed with respect to Ion implanter system 100.

Controller 190 includes I/O interface 710. I/O interface 710 is coupledto external circuitry. In some embodiments, I/O interface 710 includes akeyboard, keypad, mouse, trackball, trackpad, and/or cursor directionkeys for communicating information and commands to processor 702.

Controller 190 also includes network interface 712 coupled to theprocessor 702. Network interface 712 allows controller 190 tocommunicate with network 714, to which one or more other computersystems are connected. Network interface 712 includes wireless networkinterfaces such as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wirednetwork interface such as ETHERNET, USB, or IEEE-1394. In someembodiments, the operations as described with respect to Ion implantersystem 100 are implemented in two or more controllers 190, andinformation such as sensor information, conditioning iterationsinformation, conditioner pressure and target roughness are exchangedbetween different controllers 190 via network 714.

Controller 190 is configured to receive information related to othercomponents of the ion implanter system 100 through I/O interface 710.The information is transferred to processor 702 via bus 708 and thenstored in computer readable medium 704 as sensor parameter 716.Controller 190 is configured to receive information related to thetarget temperature and threshold temperature through I/O interface 710.In some embodiments, the target and threshold temperature information isreceived from an operator. The information is stored in computerreadable medium 704 as target temperature parameter 718 and thresholdtemperature parameter 720.

The advantages and features of the disclosure are further appreciablethrough the following example embodiments:

In some embodiments, an ion source of an ion implanter includes a sourcearc chamber having a conductive first end wall, a conductive second endwall, and a conductive sidewall defining an inner chamber space. Arepellent electrode is positioned in the inner chamber space and issecured to the first end wall through a shaft element of an insulatormaterial. The repellent electrode includes a repellent surface thatsubstantially mirrors a shape of the inner chamber space in atransversal plane where the repellent surface is positioned with a gapspace separating the repellent electrode from the conductive sidewall ofthe source arc chamber. A cathode electrode id positioned in the innerchamber space and is secured to one or more of the conductive second endwall or the conductive sidewall.

In some embodiments, an ion source of an ion implanter includes a sourcearc chamber having a conductive first end wall, a conductive second endwall, and a conductive sidewall partially defining an inner chamberspace. A repellent electrode includes a repellent body and a shaftelement. The repellent body is positioned within the inner chamberspace. The shaft element passes through the first end wall and issecured to the source arc chamber. A gap space between the repellentbody and the conductive sidewall of the source arc chamber issubstantially uniform in size from different directions. A cathodeelectrode is positioned in the inner chamber space.

In some embodiments, an ion implanter includes an ion source module thatgenerates ions. The ion source module includes a source arc chamber anda cathode electrode and a repellent electrode positioned within an innerchamber space of the source arc chamber. The repellent electrodeincludes a substantially rectangular repellent surface that fits theinner chamber space with a gap space between the repellent surface andthe source arc chamber maintaining a size of less than 2 mm in alldirections. An ion extracting module extracts the ions out of the ionsource module.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. An ion source for an ion implanter, comprising: asource arc chamber having a conductive first end wall, a conductivesecond end wall, and a conductive sidewall defining an inner chamberspace; a repellent electrode positioned in the inner chamber space andsecured to the first end wall through a shaft element of an insulatormaterial, the repellent electrode including a repellent surface thatsubstantially mirrors a shape of the inner chamber space in atransversal plane where the repellent surface is positioned with a gapspace separating the repellent electrode from the conductive sidewall ofthe source arc chamber; and a cathode positioned in the inner chamberspace and secured to one or more of the conductive second end wall orthe conductive sidewall.
 2. The ion source of claim 1, wherein the shapeof the inner chamber space in the transversal plane is substantiallyrectangular and the repellent surface is substantially rectangular andis smaller than the shape of inner chamber space in the transversalplane.
 3. The ion source of claim 2, wherein each side of the repellentsurface is smaller than a corresponding side the inner chamber space inthe transversal plane by substantially a same amount.
 4. The ion sourceof claim 3, wherein each side of the repellent surface is smaller thanthe corresponding side of the inner chamber space in the transversalplane by about 1 mm to about 2 mm.
 5. The ion source of claim 1, whereinthe repellent surface is tungsten.
 6. The ion source of claim 1, whereinthe shaft element includes a first portion and a second portion, thefirst portion being closer to the repellent surface than the secondportion and including a larger diameter than the second portion.
 7. Theion source of claim 6, wherein the first portion has a length less thana length of the second portion.
 8. The ion source of claim 1, whereinthe shaft element includes a ceramic material.
 9. The ion source ofclaim 1, wherein the second end wall is opposite to the first end wall,and the cathode is secured to the second end wall.
 10. The ion source ofclaim 1, wherein the cathode electrode includes a filament element. 11.The ion source of claim 1, wherein the repellent surface is tungsten.12. An ion source for an ion implanter, comprising: a source arc chamberhaving a conductive first end wall, a conductive second end wall, and aconductive sidewall partially defining an inner chamber space; arepellent electrode including a repellent body and a shaft element, therepellent body positioned within the inner chamber space, the shaftelement passing through the first end wall and secured to the source arcchamber, a distance between the repellent body and the conductivesidewall of the source arc chamber being substantially uniform atdifferent edge portions of the repellent body; and a cathode electrodepositioned in the inner chamber space.
 13. The ion source of claim 12,wherein the inner chamber space is substantially rectangular in atransversal cross-sectional plane adjacent to the repellent body, andthe repellent body is substantially rectangular and has a smaller areasize than an area size of the inner chamber space in the transversalcross-sectional plane.
 14. The ion source of claim 13, wherein therepellent body includes rounded corners.
 15. The ion source of claim 14,wherein the repellent body includes a rounded corner on a surface of therepellent body.
 16. The ion source of claim 14, wherein the repellentbody includes a rounded corner between an edge and a surface of therepellent body.
 17. The ion source of claim 12, wherein repellent bodyincludes a surface shape that mirrors a shape of the inner chamber spacein a cross-sectional plane.
 18. The ion source of claim 12, wherein thedistance between the repellent body and the conductive sidewall of thesource arc chamber is in a range between about 1 mm and about 2 mm. 19.An ion implanter, comprising: an ion source module that in operationgenerates ions, the ion source module having: a source arc chamberhaving an inner chamber space; a cathode electrode positioned in theinner chamber space; and a repellent electrode positioned within theinner chamber space, the repellent electrode including a substantiallyrectangular repellent surface that fits within the inner chamber spacewith a distance between an edge of the repellent surface and an sidewallof the inner chamber space being less than about 2 mm; and an ionextracting module that extracts the ions out of the ion source module.20. The ion implanter of claim 19, wherein the substantially rectangularrepellent surface includes rounded corners.